Download HDTV (High Definition Television)

HDTV
Technology
Outline
•Introduction
•HD-History
•Architecture
•Characteristics of HD standard
•Difference b/w HD & Analog
•Future of HD
•Summary
•Conclusion
•Refrences
WHY HD
To Overcome Limitations
of Analog Television
• Noise free pictures
• Higher resolution images
Widescreen / HDTV
• No Ghosting
• Enhanced Sound Services
• Other Data services.
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High Definition Television
DEFINITION: HDTV is generally recognized as a digital
video broadcast with a minimum resolution of 1280
pixels wide and 720 pixels high, a rate of 30 or more
frames/second and usually an aspect ratio of 16:9.
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HDTV History
• Early 1980’s:
– Japan created analog HDTV
• Mid-1980s:
– US, trying to stay competitive, decided to go
digital
– Congress gave stations a separate channel for
transition to digital broadcast with the goal of all
stations using digital broadcasts by 2006.
Currently...
• Less than 15% of US homes have HDTV
capabilities
• Approximately 21% of stations have digital
broadcasts
High Definition Television
A standard definition analog television uses a
cathode ray tube with an electron gun to guide
the path of an electron beam to “paint” 480
vertical lines across the face of the screen. Each
time the beam strikes a dot of phosphor, light is
produced. For a color television set, each spot
consists of a group of three phosphor elements;
one for each primary color.
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HOW HD WORK
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Implementation - Display technologies
•
Plasma – Like LCD monitors, plasma HDTV sets are thin and are made up of cells
that correspond to pixels sandwiched between glass plates. Plasma cells contain three
separate gas-fill sub-cells, one for each color. When a current is applied to a sub-cell,
it ionizes the gas emitting ultraviolet light. The ultraviolet light in turn excites
fluorescent substances in the sub-cells that emit red, blue or green light.
•
DLP – Digital light processing is a technology used in projection displays. In DLP
monitors, light is reflected off an array of microscopic hinged mirrors. Each tiny
mirror corresponds to a visible pixel. The light is channeled through a lens onto the
surface of the screen. Single chip DLP projectors can display 16.7 million colors. 3chip projectors can display 35 trillion colors.
•
LCoS – Similar to DLP, LCoS projection systems use liquid crystals instead of mirrors
to block light. The liquid crystals are arranged in a grid in front of a highly reflective
surface.
Motion Blur
A sequence of images such of a movie or
animation
HD TV Screen Refresh Rates
•A rate of 24 frames/second (progressive) has
been the movie film standard since the mid-20’s
•The television industry has used a rate of 60
frames/second (interlaced) since the 40’s
•Newer HDTV’s are being marketed as 120 Hz and
240 Hz using circuitry to help reduce motion blur
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Technical Aspects
Interlaced display
Frame rate conversion - 3-2 pulldown
What is a format?
Formats are described by:
Number
Number
of active pixels of active lines
per line
per frame
Scanning
mode
Picture
aspect ratio
Frame rate
Current main standards are:
SMPTE 274 M
SMPTE 296 M
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Archiving High definition
High definition video
Standard definition video
1980 pixels 1080 lines
720 pixels 576 lines
1- hour programme file size :
from374 GB to 673 GB*
1- hour programme file size :
72 GB
To archive HD, Compression
could be required.
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HDTV & SDTV Comparison
• Judging simply on pixel count, a 1080i HDTV
image is 6 - 9 times better than a standard, NTSC
image
• Audio is also improved.
HDTV & SDTV Comparison
Advantages
• By using lower-definition signals, one channel
can be split into several channels
• Extra channels used for:
– information services (datacasting)
– music
– Internet services
HDTV Features
• Provides up to 60 frames/sec screen writing
rate
• Uses MPEG-2 data compression
– source info data rate is 1.2Gbps
– broadcast data rate is 20Mbps
• Square pixels 1/4 the size of analog TV’s pixels
Type Of HDTV
Type
Advantage
Disadvantage
Cheap (if you can find one)
Heavy, max screen size limited,
soon to be obsolete
Competitive price, suitable for rooms
with high ambient light
Motion blur more apparent than
Plasma
Brighter colors, less motion blur, wider
viewing angle
More power consumption than
LCD, less competitive price
Rear Projection
Larger screen size at lower cost
More bulky then flat panel, more
components to fail
Front Projection
Best solution for screens over 60 inches
Costly installation, not suitable for
rooms with high ambient light
Direct View (CRT)
LCD
Plasma
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Connecting To Analog TV
Composite
Or S-Video
or
Composite or
(if available)
S-Video
COAX
Composite
or S-Video
From VCR
DVD
Composite
or S-Video
From VCR
VCR
Connecting To Digital TV
Digital Signal from Cable or Satellite
Component,
Composite
Or S-Video
DVD
Composite
or S-Video
From VCR
or
Component
Or HDMI
Composite or
S-Video
COAX
Cable or Satellite
VCR
Impact of HDTV
• Broadcasters & consumers spend more $
• Increased visual clarity has forced designers to spend
considerably more money on sets, set dressings
• Blu-Ray vs HD-DVD
Future of HD
• DEC 2012: All commercial stations must begin
digital broadcasts
• Move will be cheaper, quicker, and easier as
products and services become more widespread and
people grow accustomed to the new technology.
• Super HD TV
Conclusion
•
As NTSC retires, HDTV programming, products, and
production services will continue to grow exponentially.
•
HDTV has brought a more cinematic experience into
viewer’s homes and with digital cinema, delivered the film
industry a few of the benefits of television. However,
HDTV still has much lower resolution than 70mm film.
It’s a matter of time before some will begin pressuring for
another increase in quality.